Married before the end of three months β she's in the club (6)
I believe the answer is:
member
'she's in the club' is the definition.
(as in a member of a club)
'married before the end of three months' is the wordplay.
'married' becomes 'm'.
'before' means one lot of letters go next to another.
'the end of three months' becomes 'ember' (September, November and December).
'm'+'ember'='MEMBER'
(Other definitions for member that I've seen before include "Elected person" , "someone with a club" , "A body part or kind of participant" , "Limb - person belonging to a group" , "Limb; society joiner" .)